Your Only Halley's

A Lutheran minister once called comets the "thick smoke of human sins," a hypothesis that finds little support nowadays among scientists. They prefer to see comets as big dirty snowballs trailing tails of gas and enthralled by gravitation. And coming not from God but from the equally ineffable Oort cloud, a gigantic shell far beyond the solar system where aspiring comets spend eons of quiet desperation until disturbed by some celestial accident and called to race toward the sun and make men weep.

Except that men don't weep any more. Halley's Comet may have brought victory to the Normans in 1066, heralded the descent of Turkish armies on Belgrade in 1456, and, in 1910, killed Mark Twain and then Edward VII. This time around all is forgiven. After all, it knows not what it does. And we know what it is: a forlorn mass of rock and ice, a few miles across, caught in endless revolution around our sun. Now an object, not an omen, it is the source not of panic but of curiosity. Five earthly spacecraft have been sent to greet it and snap its picture.

Science has thoroughly desacrilized the universe. It is in the language. When in the last election Walter Mondale warned against militarizing "the heavens," the usage seemed quaint. After Neil Armstrong and George Lucas, what's up there now is simply "space." The heavens were a place for angels, gods and portentous messengers. Space is home to extraterrestrials, the Force and now snowballs cruising through emptiness.

Don't get me wrong. I am not pining for the days of the witch doctor. Things are much better now. There are costs to demystifying the universe and turning it over to science -- the ubiquity of Carl Sagan is among the heavier ones -- but the gain is great.

Halley's, like the rest of space, is friendly now, tamed. This will probably be the first time in history that Halley's will bring wonder unalloyed with fear. Halley's has turned into a celebration, a scientific romance.

The romance is in the return. Halley's comes back, always exactly on time. After its current pass, it will travel 3 billion miles away from Earth and then turn to revisit your children. It is the grandest reminder that an individual can behold of the constancy of nature. This, because of its cycle: it returns about every 75 years, once in a lifetime.

The sun rises regularly, too, but so often that we can't help being dulled to the wonder of its rhythm. And what rhythms, beyond that of the familiar year, really touch us? Sun spots come every 11 years, and what layman cares? Economists are forever coming up with "long waves" (50 years) and other putative business cycles. Even Freud's theory of neurosis was built on the notion of a distant return, the retun of the child to the mind of the man. Such cycles can most charitably be called speculative.

Others are merely too long. The ice age will be back too. Fit that in your calendar. Halley's alone is made to human scale. Its span is precisely a lifetime. Birth and death are perhaps the only events that match Halley's periodicity. And neither is nearly as reliable. Birth and death come with regular irregularity (to borrow a term from cardiology). Halley's you can count on.

We know, for example, absolutely nothing about what the world will be like in 2061. Except one thing. In that unimaginable year, a year whose very number has an otherworldly look, Halley's will light up the sky.

One price of demystifying the universe is that science, unlike religion, asks only how, not why. As to the purpose of things, science is silent. But if science cannot talk about meaning, it can talk about harmony. And Halley's is at once a symbol and a proof of a deep harmony of the spheres.

The great author of that harmony was Newton. And one of the earliest empirical demonstrations of his gravitational theories was provided by his friend, Edmond Halley. Twenty-three years after the great comet of 1682, Halley deciphered its logic. He predicted its return in 1758. Halley died 17 years before he could be proved right. The return of the comet was a sensation. It made Halley immortal. True to its nature, science wed the comet forever to the man who did not discover it, but was the first to understand it.

This time around, there will be no sensation. Halley's will give one of the worst shows ever. This may be its dimmest apparition in more than 2,000 years. What we will celebrate, then, is not the spectacle, but the idea.

Halley's is a monument to science, a spokesman for its new celestial harmonies -- and an intimation of mortality. It is at once recurring and, for us individually, singular. This will be my only Halley's and, if you're old enough to read this without moving your lips, your last one too, I'm afraid.

Halley's speaks to me especially acutely. As it turns around the sun, the midpoint on its journey, I will be marking the midpoint in mine, or so say the Metropolitan Life tables. Our perihelions match. Mark Twain was rather pleased with the fact that he came in with Halley's and would go out with it. Ashes to ashes, Oort to Oort. Hail Halley's.